Researchers have found an association between certain occupations and increased breast cancer risk. (Image: BEZERGHEANU Mircea/iStockphoto.com)

Certain occupations with potentially high exposures to carcinogens and endocrine disruptors are associated with an increased risk of breast cancer, say researchers whose findings appear today online in Environmental Health.

The researchers, using data collected from 2002 to 2008, found that working in automotive plastics manufacturing increased breast cancer risk by 168%; food canning, by 135%; metalworking, by 73%; and agriculture, by 36%. Premenopausal breast cancer risk was highest for women who had worked in food canning (470%) or automotive plastics (376%). In other sectors, such as construction, petrochemicals, printing, and textile manufacturing, there was a lack of statistical power to draw conclusions about exposure associations with breast cancer.

Breast cancer is the most frequent cancer diagnosis among women in industrialized countries, and North American rates are among the highest in the world. Lifetime exposures to endogenous estrogen affect the risk of breast cancer, and exogenous estrogenic compounds may do so as well. Yet very little research exploring the possible link between occupational exposures and breast cancer risk has been conducted.

To add to the literature on occupational cancer risk, the authors of the new study conducted a population-based case-control study in southern Ontario, Canada, a region with a stable population and diverse modern agriculture and industry. The study included 1006 breast cancer cases and 1146 randomly selected and matched community controls. The researchers used interviews and surveys to collect data on participants’ occupational and reproductive histories. All jobs were coded for their likelihood of exposure to carcinogens and endocrine disruptors, and patients’ tumor pathology regarding endocrine receptor status was assessed.

The researchers also discussed possible exposures based on occupation. They noted that workers in agriculture may be exposed to pesticides that cause cancer in laboratory animal testing; automotive plastics workers are exposed to many plastics that have been found to release estrogenic chemicals; and food canning workers may inhale bisphenol A (BPA), which can be released into the air when cans are washed prior to use.